Notes on Geography: Where’s Metropolis?
DC has never been perfectly consistent about the location of some of its more famous fictional cities, like Metropolis and Gotham. But I spotted this while reading O.M.A.C. #2:

It seems that the DCnU is taking some cues from the television series Smallville. Interstate Highway 35 stretches North-South from Laredo, Texas to Duluth, Minnesota, passing through Oklahoma, Kansas, Missouri, and Iowa. Odds are Metropolis is in Kansas, as it was in the ten-year run of Smallville, but at the very least we can narrow it’s location down to one of these six Mid-Western states.